Ah, the joys of E.Y.E.
See, this game rocks because what you've described right now, BFEL, is a completely viable approach.
And on the other hand, so is any other.
So let me explain. My first char was a typical jack-of-all-trades-master-of-none stats wise and that felt pretty obviously in-game. I've had fun with him however.
My second character was a hacker. And guess what, that works as well! Once you get the ropes of hacking it's quite fun! Even though I admit, yes, it is a bit repetitive...Still, I can easily say I've spent more than half of my 60+ Steam hours playing with that char. It definitely helps if you specialize and yeah, you can't expect you'll hit the sweet spot on your first campaign walkthrough (unless you spend a ridiculous time just doing temple missions). But that's how this game is - you are absolutely encouraged to make many different characters, try different builds, walk different paths... There is a very high limit of levels (249?? Something like that, last time I checked) and theoretically you could try and put stat points in each stats equally, try each weapon, each PSY power with just one character... But why SHOULD you? Unlike levels, stats have no caps! So go crazy! Make a speedy, katana wielding hacker! Slow, tanky, revolver-using doctor! Stealthy psy-user! Try it all!
And let the madness be all-consuming.
Oh yeah, and hit me up on pm if you fancy a co-op.
edit: do also note, I am officially obsessed with this game and my opinion IS bound to be biased.